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author | leilei.lin <leilei.lin@alibaba-inc.com> | 2018-03-06 17:36:37 +0800 |
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committer | Ingo Molnar <mingo@kernel.org> | 2018-03-12 15:28:51 +0100 |
commit | 33801b94741d6c3be9713c10aa627477216c21e2 (patch) | |
tree | b241236cf8773658ce499c85a483199675fb4f82 | |
parent | 8d5bce0c37fa10f21dbdd6a6d8fcba85202fe24e (diff) | |
download | linux-stable-33801b94741d6c3be9713c10aa627477216c21e2.tar.gz linux-stable-33801b94741d6c3be9713c10aa627477216c21e2.tar.bz2 linux-stable-33801b94741d6c3be9713c10aa627477216c21e2.zip |
perf/core: Fix installing cgroup events on CPU
There's two problems when installing cgroup events on CPUs: firstly
list_update_cgroup_event() only tries to set cpuctx->cgrp for the
first event, if that mismatches on @cgrp we'll not try again for later
additions.
Secondly, when we install a cgroup event into an active context, only
issue an event reprogram when the event matches the current cgroup
context. This avoids a pointless event reprogramming.
Signed-off-by: leilei.lin <leilei.lin@alibaba-inc.com>
[ Improved the changelog and comments. ]
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Cc: brendan.d.gregg@gmail.com
Cc: eranian@gmail.com
Cc: linux-kernel@vger.kernel.org
Cc: yang_oliver@hotmail.com
Link: http://lkml.kernel.org/r/20180306093637.28247-1-linxiulei@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
-rw-r--r-- | kernel/events/core.c | 46 |
1 files changed, 35 insertions, 11 deletions
diff --git a/kernel/events/core.c b/kernel/events/core.c index f98c0f88cc94..969f865f9f1c 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -937,27 +937,39 @@ list_update_cgroup_event(struct perf_event *event, if (!is_cgroup_event(event)) return; - if (add && ctx->nr_cgroups++) - return; - else if (!add && --ctx->nr_cgroups) - return; /* * Because cgroup events are always per-cpu events, * this will always be called from the right CPU. */ cpuctx = __get_cpu_context(ctx); - cpuctx_entry = &cpuctx->cgrp_cpuctx_entry; - /* cpuctx->cgrp is NULL unless a cgroup event is active in this CPU .*/ - if (add) { + + /* + * Since setting cpuctx->cgrp is conditional on the current @cgrp + * matching the event's cgroup, we must do this for every new event, + * because if the first would mismatch, the second would not try again + * and we would leave cpuctx->cgrp unset. + */ + if (add && !cpuctx->cgrp) { struct perf_cgroup *cgrp = perf_cgroup_from_task(current, ctx); - list_add(cpuctx_entry, this_cpu_ptr(&cgrp_cpuctx_list)); if (cgroup_is_descendant(cgrp->css.cgroup, event->cgrp->css.cgroup)) cpuctx->cgrp = cgrp; - } else { - list_del(cpuctx_entry); - cpuctx->cgrp = NULL; } + + if (add && ctx->nr_cgroups++) + return; + else if (!add && --ctx->nr_cgroups) + return; + + /* no cgroup running */ + if (!add) + cpuctx->cgrp = NULL; + + cpuctx_entry = &cpuctx->cgrp_cpuctx_entry; + if (add) + list_add(cpuctx_entry, this_cpu_ptr(&cgrp_cpuctx_list)); + else + list_del(cpuctx_entry); } #else /* !CONFIG_CGROUP_PERF */ @@ -2489,6 +2501,18 @@ static int __perf_install_in_context(void *info) raw_spin_lock(&task_ctx->lock); } +#ifdef CONFIG_CGROUP_PERF + if (is_cgroup_event(event)) { + /* + * If the current cgroup doesn't match the event's + * cgroup, we should not try to schedule it. + */ + struct perf_cgroup *cgrp = perf_cgroup_from_task(current, ctx); + reprogram = cgroup_is_descendant(cgrp->css.cgroup, + event->cgrp->css.cgroup); + } +#endif + if (reprogram) { ctx_sched_out(ctx, cpuctx, EVENT_TIME); add_event_to_ctx(event, ctx); |